Systems and methods for wide voltage DC-DC power conversion

Abstract

In at least one embodiment, a DC-DC power converter comprises a primary circuit coupled to a DC input voltage, a secondary circuit coupled to a DC output voltage, and a transformer isolating the primary from the secondary circuit. The primary circuit comprises a first and second circuit branch. The first circuit branch comprises a plurality of switches, a diode, and a reconfiguration switch. The second circuit branch comprises a plurality of switches, and a plurality of diodes. The reconfiguration switch is operable to switch the primary circuit between a first mode and a second mode, wherein the primary circuit operates as a full-bridge circuit in the first mode and the primary circuit operates as a half-bridge circuit in the second mode.

We claim: 
     
         1 . A direct current (DC)-DC power converter comprising:
 a primary circuit coupled to an input voltage, the input voltage being DC type, the primary circuit operable to convert the input voltage into an AC voltage;   a secondary circuit coupled to the primary circuit, the secondary circuit operable to convert the AC voltage into an output voltage, the output voltage being DC type;   a transformer isolating the primary circuit from the secondary circuit, the transformer comprising a predetermined number of turns;   an energy transfer element interfacing the primary circuit with the transformer;   a first plurality of capacitors connected in series with each other, the first plurality of capacitors being connected in parallel with the input voltage;   the primary circuit comprising a first primary circuit branch and a second primary circuit branch; wherein:   the first primary circuit branch is connected in parallel with the input voltage and comprises a first plurality of primary switches and a first branch primary diode;   the second primary circuit branch is connected in parallel with the input voltage and comprises a second plurality of primary switches and a plurality of second branch primary diodes coupled to each other; and   wherein one of the first primary circuit branch and the secondary circuit comprises a reconfiguration switch, wherein the reconfiguration switch is operable to switch the power converter between a first mode and a second mode, and wherein the power converter operates as a full bridge circuit in the first mode and the power converter operates as a half bridge circuit in the second mode.   
     
     
         2 . The DC-DC power converter of  claim 1 , further comprising a second plurality of capacitors connected in series with each other, the second plurality of capacitors being connected in parallel with the output voltage; and wherein the secondary circuit further comprises:
 a first secondary circuit branch and a second secondary circuit branch;   the first secondary circuit branch being connected in parallel with the output voltage and comprising a first plurality of secondary switches and a first plurality of secondary diodes coupled to each other; and   the second secondary circuit branch being connected in parallel with the output voltage and comprising a second plurality of secondary switches and a second plurality of secondary diodes coupled to each other.   
     
     
         3 . The DC-DC power converter of  claim 2 , wherein the first primary circuit branch comprises the reconfiguration switch and wherein:
 the first plurality of capacitors connects to the input voltage at a positive input node and a negative input node;   the first plurality of capacitors further comprises a first and a second input DC-link capacitors, the first and the second input DC-link capacitors defining a floating neutral node at a first common connection point;   the first primary circuit branch comprises:
 a first output node, a first primary junction node, and a second primary junction node, wherein: 
 a first switch from the first plurality of primary switches is connected between the positive input node and the first primary junction node; 
 a second switch from the first plurality of primary switches is connected between the first primary junction node and the first output node; 
 a third switch from the first plurality of primary switches is connected between the second primary junction node and the first output node; 
 a fourth switch from the first plurality of primary switches is connected between the second primary junction node and the negative input node; 
 the first branch primary diode is connected between the first primary junction node and the floating neutral node; and 
 the reconfiguration switch is connected between second primary junction node and the floating neutral node; and 
 the secondary circuit comprises a rectifying circuit. 
   
     
     
         4 . The DC-DC power converter of  claim 3 , wherein the second primary circuit branch comprises:
 a second output node, a third primary junction node, and a fourth primary junction node, wherein:   a first switch from the second plurality of primary switches is connected between the positive input node and the third primary junction node;   a second switch from the second plurality of primary switches is connected between the third primary junction node and the second output node;   a third switch from the second plurality of primary switches is connected between the fourth primary junction node and the output node;   a fourth switch from the second plurality of primary switches is connected between the fourth primary junction node and the negative input node;   a first diode from the plurality of second primary diodes is connected between the third primary junction node and the floating neutral node; and   a second diode from the plurality of second primary diodes is connected between the fourth primary junction node and the floating neutral node.   
     
     
         5 . The DC-DC power converter of  claim 4 , wherein:
 the second plurality of capacitors connects with the output voltage at an output positive node and an output negative node;   the second plurality of capacitors comprises at least a first and second output DC-link capacitor and the capacitors defining a floating output neutral node at a second common connection point; and   the secondary circuit comprises a first and second secondary circuit branch; and   wherein the first and second secondary circuit branches each comprise a plurality of secondary switches and a plurality of secondary diodes coupled to each other and are connected in parallel with the output voltage.   
     
     
         6 . The DC-DC power converter of  claim 5 , wherein:
 the first and second secondary circuit branches each comprise:
 an input node, a first secondary junction node, and a second primary junction node, wherein: 
 a first switch from the plurality of secondary switches is connected between the output positive node and the first secondary junction node; 
 a second switch from the plurality of secondary switches is connected between the first secondary junction node and the input node; 
 a third switch from the plurality of secondary switches is connected between the second junction node and the input node; 
 a fourth switch from the plurality of secondary switches is connected between the second junction node and the output negative node; 
 a first diode from the plurality of secondary diodes is connected between the first junction node and the floating output neutral node; and 
 a second diode from the plurality of secondary diodes is connected between second junction node and the floating output neutral node. 
   
     
     
         7 . The DC-DC power converter of  claim 1 , wherein the energy transfer element comprises an inductor. 
     
     
         8 . The DC-DC power converter of  claim 1 , wherein the energy transfer element comprises an inductor connected in series with a capacitor. 
     
     
         9 . The DC-DC power converter of  claim 1 , wherein the energy transfer element comprises a first inductor, a second inductor connected to the first inductor at a common point, and a capacitor connected at the common point. 
     
     
         10 . The DC-DC power converter of  claim 1 , wherein the energy transfer element comprises a first inductor connected in series with a capacitor and a second inductor connected in parallel across a primary winding of the transformer. 
     
     
         11 . The DC-DC power converter of  claim 1 , wherein the secondary circuit comprises:
 a first secondary switch, a second secondary switch, a third secondary switch, and a fourth secondary switch arranged in a full-bridge configuration; and   a DC-link capacitor connected in parallel across the output voltage.   
     
     
         12 . The DC-DC power converter of  claim 1 , wherein the secondary circuit comprises:
 a first secondary switch and a second secondary switch arranged in a half-bridge configuration; and   a first DC-link capacitor and a second DC-link capacitor connected in series with each other, and a series combination of the first DC-link capacitor and the second DC-link capacitor connected in parallel across the output voltage.   
     
     
         13 . The DC-DC power converter of  claim 1 , wherein the secondary circuit comprises:
 four switches and two diodes arranged in a neutral point clamped configuration; and   a series combination of a first DC-link capacitor and a second DC-link capacitor connected in parallel across the output voltage.   
     
     
         14 . The DC-DC power converter of  claim 1 , wherein the secondary circuit comprises:
 a first circuit branch comprising six switches arranged in an active neutral point clamped configuration;   a second circuit branch comprising six switches arranged in an active neutral point clamped configuration; and   a series combination of a first DC-link capacitor and a second DC-link capacitor connected in parallel across the output voltage.   
     
     
         15 . The DC-DC power converter of  claim 1 , wherein the secondary circuit comprises:
 six switches arranged in an active neutral point clamped configuration; and   a series combination of a first DC-link capacitor and a second DC-link capacitor connected in parallel across the output voltage.   
     
     
         16 . The DC-DC power converter of  claim 1 , wherein the secondary circuit comprises:
 a first circuit branch comprising four switches arranged in a flying capacitor configuration;   a second circuit branch comprising four switches arranged in a flying capacitor configuration; and   a DC-link capacitor connected in parallel across the output voltage.   
     
     
         17 . The DC-DC power converter of  claim 1 , wherein the secondary circuit comprises:
 four switches arranged in a flying capacitor configuration; and   a series combination of a first DC-link capacitor and a second DC-link capacitor connected in parallel across the output voltage.   
     
     
         18 . The DC-DC power converter of  claim 1 , wherein the secondary circuit comprises:
 a first switch, a second switch, a third switch and a fourth switch connected in series across the output voltage; and   a series combination of a first DC-link capacitor and a second DC-link capacitor connected in parallel across the output voltage.   
     
     
         19 . The DC-DC power converter of  claim 1 , wherein when a voltage swing associated with the output voltage is greater than a voltage swing associated with the input voltage, the secondary circuit comprises the reconfiguration switch. 
     
     
         20 . The DC-DC power converter of  claim 1 , wherein the secondary circuit operates in a five-level operation to produce five voltage levels at a secondary of the transformer. 
     
     
         21 . The DC-DC power converter of  claim 20 , wherein the primary circuit operates in a two-level operation to produce two output voltage levels at a primary of the transformer. 
     
     
         22 . The DC-DC power converter of  claim 20 , wherein the primary circuit operates in a three-level operation to produce three output voltage levels at a primary of the transformer based on operating in the first mode. 
     
     
         23 . The DC-DC power converter of  claim 20 , wherein the primary circuit operates in a five-level operation to produce five output voltage levels at a primary of the transformer based on operating in the first mode. 
     
     
         24 . The DC-DC power converter of  claim 1 , wherein a direction of power transfer between the input and the output voltages can be controlled by varying a phase shift in a modulation scheme. 
     
     
         25 . The DC-DC power converter of  claim 1 , wherein the power converter is coupled to an AC-DC module for converting a source AC input voltage into the input voltage of the power converter. 
     
     
         26 . A Direct Current (DC)-Alternating Current (AC) power converter circuit comprising:
 an input voltage, the input voltage being DC type, the primary circuit operable to convert the input voltage into an AC voltage;   a plurality of capacitors connected in series with each other, a series combination of the plurality of capacitors being connected in parallel with the input voltage;   a first circuit branch and a second circuit branch;   the first branch, connected in parallel with the input voltage, comprising a first plurality of switches, a first diode, and a reconfiguration switch;   the second branch, connected in parallel with the input voltage, comprising a second plurality of switches and a second plurality of diodes; and   wherein the reconfiguration switch is operable to switch the circuit between a first mode and a second mode, and wherein the circuit operates as a full bridge circuit in the first mode and the circuit operates as a half bridge circuit in the second mode.   
     
     
         27 . The DC-AC converter circuit of  claim 26 , wherein:
 the plurality of capacitors connects to the input voltage at a positive input node and a negative input node;   the plurality of capacitors further comprises a first and second input DC-link capacitor, the first and the second capacitors defining a floating neutral node at a first common connection point; and   the first circuit branch comprises:
 a first output node, a first junction node, and a second junction node, wherein: 
 a first switch from the first plurality of switches is connected between the positive input node and the first junction node, 
 a second switch from the first plurality of switches is connected between the first junction node and the first output node; 
 a third switch from the first plurality of switches is connected between the second junction node and the first output node; 
 a fourth switch from the first plurality of switches is connected between the second junction node and the negative input node; 
 a first diode from the plurality of first diodes is connected between the first primary junction node and the floating neutral node; and 
 the reconfiguration switch is connected between the second junction node and the floating neutral node. 
   
     
     
         28 . The DC-AC converter circuit of  claim 27 , wherein the second circuit branch comprises:
 a second output node, a third junction node, and a fourth junction node, wherein:   a first switch from the second plurality of switches is connected between the positive input node and the third junction node,   a second switch from the second plurality of switches is connected between the third junction node and the second output node;   a third switch from the second plurality of switches is connected between the fourth junction node and the second output node;   a fourth switch from the second plurality of switches is connected between the fourth junction node and the negative input node;   a first diode from the second plurality of diodes is connected between the third junction node and the floating neutral node; and   the second diode from the second plurality of diodes is connected between the fourth junction node and the floating neutral node.   
     
     
         29 . The DC-AC power converter of  claim 28 , wherein the power converter operates in a two-level operation to produce two output voltage levels across the first output node and the second output node. 
     
     
         30 . The DC-AC power converter of  claim 28 , wherein the primary circuit operates in a three-level operation to produce three output voltage levels across the first output node and the second output node based on operating in the first mode. 
     
     
         31 . The DC-AC power converter of  claim 28 , wherein the primary circuit operates in a five-level operation to produce five output voltage levels across the first output node and the second output node based on operating in the first mode. 
     
     
         32 . A method of operating a primary circuit of a DC-DC converter in a half-bridge mode, wherein the DC-DC converter comprises:
 the primary circuit coupled to an input voltage, the input voltage being DC type, the primary circuit operable to convert the input voltage into an AC voltage;   a secondary circuit coupled to the primary circuit, the secondary circuit operable to convert the AC voltage into an output voltage, the output voltage being DC type;   a first and second input DC-link capacitor, the first and second capacitors connected in series with each other, a series combination of the first and second capacitors connected in parallel with the input voltage at a positive input node and a negative input node, the first and the second capacitors defining a floating neutral node at a common connection point;   a transformer isolating the primary circuit from the secondary circuit;   the primary circuit comprising a first primary circuit branch and a second primary circuit branch; wherein:   the first primary circuit branch is connected in parallel with the input voltage and comprises a first, a second, a third, and a fourth primary switch, a first branch primary diode, a reconfiguration switch, and first output node; and   the second primary circuit branch is connected in parallel with the input voltage and comprises a fifth, sixth, seventh, and eighth primary switch, a third and fourth branch primary diode coupled to each other, and a second output node;   
       the method comprising:
 activating the third switch and the reconfiguration switch to allow a path of current flow between the first output node and the floating neutral node though the third switch and the reconfiguration switch; 
 activating a fifth and sixth switch to allow a path of current flow between the positive input node to the second output node through the fifth and sixth switches; 
 de-activating the fifth and sixth switches to divert the path of current flow from the fifth and sixth switches to body diodes contained within a seventh and eighth switch; 
 activating the seventh and eighth switches to allow a path of current flow from the input negative node to the second output node through the seventh and eighth switches; 
 deactivating the seventh and eighth switches to divert the path of current flow from the seventh and eighth switches to body diodes contained within the fifth and sixth switches.